标题: From Prep [打印本页] 作者: Jasmine10 时间: 2010-4-21 12:33 标题: From Prep Excuse me that I type in English, because I'm using school computer now. I need help~~ NN brothers and sisters, please help me on the CR as following. Thanks so much~
It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite. However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets. So, even if bacteria did arrive on Earth from Mars, they must have died out.
The argument is most vulnerable to which of of the following criticisms?
A. It fails to establish whether bacteria actually developed on Mars. B. It fails to to establish how likely it is that Martian bacteria were transported to Earth. C. It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth. D. It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria. E. It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.
I chose D, however, the correct one is E... E.作者: ruimiss 时间: 2010-4-21 20:07
额。。。我是这样理解的。 如何削弱原文，那就要说那些从火星来的细菌并没有死。
E说,是否起源于地球的细菌后来died out，如果是died out了，那么地球上的no two bacterial strains on Earth are different enough to have arisen on different planets就有可能都是来自火星上的细菌，因为地球自己的细菌死光了。从而就说明火星上的细菌到地球来后并没有died out，削弱了文章。
想了想为什么E不对
It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out
它只是说could have been，没有说是否所有地球上的细菌都die out
则
1. all bacteria that originated on Earth later died out --> 现存的都是来自Mars的细菌，因此才测不出不同的蛋白质 --> 所以不能得出来自MARS的细菌都die out了 . 可以削弱原文结论。
2. some bacteria that originated on Earth later died out --> 但是测不出不同的蛋白质 --> 可以推测来自MARS的细菌都die out了。
支持了原文结论
